The subject matter herein relates generally to electrical relay devices.
Electrical relay devices are generally electrically operated switches used to control the presence or absence of current flowing through a circuit between electrical components, such as from a power source to one or more electrical components that receive power from the power source. The power source may be one or more batteries, for example. Some electrical relays use an electromagnet to mechanically operate a switch. The electromagnet is configured to physically translate a movable electrical contact relative to one or more stationary contacts. The movable electrical contact may form or close a circuit (allowing current to flow through the circuit) when the movable contact engages one or more of the stationary contacts. Moving the movable electrical contact away from the stationary contact(s) breaks or opens the circuit (ceasing the flow of current through the circuit).
At least some electrical relay devices include a ferromagnetic element that is disposed at least proximate to the electromagnet such that an induced magnetic field applies a magnetic force upon the ferromagnetic element that translates the ferromagnetic element relative to the electromagnet. The ferromagnetic element is coupled to a shaft, which extends from the ferromagnetic element to the movable electrical contact. The shaft is coupled to both the ferromagnetic element and the movable electrical contact. Therefore, movement of the ferromagnetic element due to the induced electrical field causes movement of the shaft and the movable electrical contact towards and away from the one or more stationary contacts, forming and braking the circuit as described above.
Known electrical relay devices have some disadvantages. For example, some electrical relay devices are sealed from the external environment, which protects the components of the relay device against dust, humidity, and other contaminants. However, known sealed electrical relay devices risk damage and/or destruction due to build-up of temperature and/or pressure within the sealed region of the relay device. Such a build-up of temperature and/or pressure may occur as a result of a fault in which too much electrical energy (for example, current and/or voltage) is supplied to the relay device. For example, an electrical relay device may be rated for handling 420 volts (V) and 135 amperes (A), but, due to a fault in which an up-stream resistor is defective and fails to limit the current, for example, the relay device may receive too much electrical energy, such as 420 V and 400 A. The high current may heat up the gas in the sealed relay device, causing the pressure to increase as the gas expands. As the pressure exceeds the structural limits of the relay device, the relay device may bulge and deform. Eventually, the relay device may burst or explode, destroying the relay device and causing the relay device to be immediately inoperable.
A need remains for an electrical relay device that is better able to control the pressure within the sealed region to prohibit the electrical relay device from bursting due to a fault such that the electrical relay device is at least partially functional after experiencing a fault.